It is known, as for example from U.S. Pat. No. 3,471,134 or German Pat. Publication No. 2,615,431, to support a workpiece in a furnace on internally cooled support tubes. Two sets of such tubes are frequently provided to form a walking-beam conveyor.
In order to prevent the supports from heating excessively, they are formed entirely as tubes through which a fluid coolant such as air or steam is circulated. Normally this circulation takes place from one end to the other of the horizontal tubes of such a support system. Since considerable thermal expansion takes place in these arrangements it is normally necessary to support these horizontal tubes between their ends by means of vertical tubes whose lower ends are supported on carriages or the like that allow them to travel limitedly in the longitudinal direction of the horizontal tubes.
To cool these vertical support tubes as well as the horizontal tubes, a small-diameter diversion pipe is provided at the joint between the upper end of each of the vertical tubes and the respective horizontal tube. Such a diversion pipe has an upper leg opening in the upstream direction, that is against the direction of flow through the horizontal tube, and a lower leg opening downwardly into the center of the respective tube. This lower leg is received with all-around clearance in the vertical tube. Thus some of the fluid moving along the horizontal tube will enter the intake end of the diversion tube and will be injected from the output end thereof into the vertical tube. This diverted coolant will cool the vertical tube and then rise in the annular space around the diversion pipe to rejoin the stream flowing along the horizontal tube. Such an arrangement ensures that even the vertical support legs for the horizontal tubes will be sufficiently cooled to prevent their weakening.
A disadvantage of this type of arrangement is that considerable turbulence is created at the joint where the upper end of each of the vertical tubes is connected to the respective horizontal tube. This turbulence, caused at least in part by the coolant stream rising out of the vertical tube, reduces overall flow through the system and, therefore, reduces cooling efficiency therein.